Abstract:

Graphene oxide (GO) can be quickly deposited on a positively charged porous matrix via a layer-by-layer self-assembly strategy because GO nanosheets contain rich negatively charged, oxygen-containing function groups, such as COOH. In this paper, the GO-ceramics composite nanofiltration membrane was prepared via layer-by-layer deposition of GO solution and eolyethyleneimine (PEI) solution alternately, and then cross-linked by epoxy chloropropane (ECH) on 3-aminopropyltriethoxysilane-modified porous Al₂O₃ supports. The optimum preparation conditions were: PEI 5g·L^-1, pH=9; NaCl 0.3 mol·L^-1; GO 0.6 mg·L^-1, pH 4.5; ECH 6.25 ml·L^-1 and heat treatment 50℃/70 min. Under the conditions of 0.6 MPa, when the self-assembly layer number increased from 1 to 4, the rejection to 2 g·L^-1 MgCl₂ were 90.16%, 93.71%, 97.54%, and 92.93% respectively,and the flux of self-assembled monolayer membrane was 21.92 L·m^-2·h^-1. The rejection orders of inorganic salts of GO-ceramics composite nanofiltration membrane were as follows: MgCl₂ >MgSO₄ >NaCl >Na₂SO₄, therefore they showed the typical positively charged nanofiltration membrane characteristics.

Key words: graphene oxide, layer-by-layer self-assembly, nanofiltration, positively charged, membrane, filtration

摘要：

氧化石墨烯（GO）的片层边缘含有 COOH等含氧官能团，因而带负电荷，可以在带正电荷多孔基体上通过层层自组装实现快速沉积。以由3-氨丙基三乙氧基硅烷（APTES）修饰的多孔氧化铝管式陶瓷膜为基膜，令GO和聚乙烯亚胺（PEI）以溶液形态在其表面交替沉积实现自组装，继以环氧氯丙烷（ECH）交联之，制备新型氧化石墨烯-陶瓷复合纳滤膜。最佳制备工艺是，PEI浓度5 g·L^-1、pH=9，NaCl浓度0.3 mol·L^-1，GO浓度0.6 mg·ml^-1、pH 4.5，层数2层，ECH用量6.25 ml·L^-1，50℃条件下处理70 min。层数为1～4层的自组装膜在0.6 MPa操作压力下对2 g·L^-1的MgCl₂的截留率分别为90.16%、93.71%、97.54%、92.93%，其中1层自组装膜的渗透通量为21.92 L·m^-2·h^-1。氧化石墨烯-陶瓷复合纳滤膜对4种无机盐的截留率大小为MgCl₂ >MgSO₄ > NaCl >Na₂SO₄，符合典型正电荷纳滤膜的特征。

关键词: 氧化石墨烯, 层层自组装, 纳滤, 荷正电, 膜, 过滤